Herbert Feigl, The "Mental" and the "Physical": The Essay and a Postscript (1967).
VI. A Budget of Unsolved Problems. Suggestions for Further Analyses and Research Although I have proposed what I believe to be at least a fairly circumspect sketch of an adequate solution of the mind-body problems, there are a number of specific component issues which require a great deal of further clarification and investigation. Since I am more interested in the continuing endeavors in this field than in having said the "last word" about it (that's almost inconceivable, in philosophy at any rate!), I shall now attempt to state and discuss succinctly a number of questions to which I have no entirely satisfactory answer at present. I should be immensely pleased if others were to take up these questions in their own work.
The foregoing analyses and discussions were intended to bring to a level of full awareness many of the repressed difficulties of our problem. I have been especially concerned to separate, as well as I could, the scientific from the philosophical issues. And I have tried to show that there are no insuperable logical difficulties for an identity theory of the mental and the physical. I shall again divide the discussion into two parts. The first (A, B, C) will be concerned with open philosophical questions and difficulties. The second (D) will appraise much more briefly the acceptability of identity theory in the light of possibly forthcoming heterodoxical scientific discoveries.